Steve Ballmer has just announced that in the first three days of being on sale, more than 4 million people have bought the Windows 8 upgrade. This doesn't count OEM installations or Microsoft's own Surface - just individual upgrades. Definitely a promising start for Windows 8, but then, these are most likely enthusiasts (I'm one of those four million), so we still don't know a whole lot. I'm patiently waiting for the response from regular consumers.

4 million is a rather paltry number considering Windows' installed base of around 1.25 billion. A measly .3% first 4 days. In contrast, Apple's installed base of 66 million had a 5% uptake of Mountain Lion in the same amount of time.